1. Field of the Invention
This invention relates to a method for removing residual hydrogen peroxide on the packing materials of foodstuff which have been sterilized with hydrogen peroxide.
2. Prior Art
Hydrogen peroxide has been widely used for bleaching foodstuff and for sterilizing packing materials, containers, etc. for foodstuff. Since it has been recently pointed out that residual hydrogen peroxide in foodstuff may have an undesirable effect on the human body, the application of hydrogen peroxide to food-industries is being limited strictly. The same holds true for hydrogen peroxide treatment for sterilizing the packing materials for foodstuff, such as food-containers, the equipment for packaging or packing. According to the Standard of Food-Additives (Notice No. 24 by Japan Welfare Ministry issued Mar. 20, 1975), it is required to remove throughly residual hydrogen peroxide on the packing equipment for foodstuff, before foodstuff comes into contact with the equipment. The method for sterilizing materials for foodstuff with hydrogen peroxide differs more or less depending on the form, kind and uses.
There was ordinarily employed a method wherein the packing materials for foodstuff were treated at high temperature with hot air, etc. to enhance sterilizing effect by generating nascent oxygen after contact with hydrogen peroxide on the materials, to remove residual hydrogen peroxide and to keep sterilizing condition till food packaging or packing process. However, this method makes it difficult to remove throughly the residual hydrogen peroxide on the packing materials for foodstuff. It was known to use enzyme or chemicals as a method for removing hydrogen peroxide in food processing. Concretely, the following methods have been proposed: an addition of a catalyst for decomposing hydrogen peroxide; an addition sodiumsulfite or sodium hydrosulfite as reducing agent; an addition of wheat bran and its water extracts in producing pickles (see the Japanese Patent Publication No. 30337/1980); and an addition of magnesium oxide etc. (see the Japanese Patent Publication No. 30338/1980).
For removing residual hydrogen peroxide on the packing materials for foodstuff which have been sterilized with hydrogen peroxide, the application of catalase or chemicals has many disadvantages; since enzyme is expensive and unstable to heat, and since sulfur-containing chemicals such as sodium monosulfite, sodium hydrosulfite, etc., are converted to sulfur dioxide to be hold as harmful substance in foodstuff.
Moreover, enzyme-and sulfur-containing chemicals have such disadvantages that they can not treat packing materials for foodstuff rapidly, because they require too long time for complete decomposition or removal of residual hydrogen peroxide.